I am almost 100% sure that i'm bisexual/pansexual. But I don't know for sure. Is there a way to be sure? How did you know you were bi/pan? Did you/how did you change mentally/emotionally/etc. when you were sure?
I am certain but there's always the stories about bisexuality being a phase, attention seeking etc. I know it's bulls**t but it still makes you have doubts.